But I never thought of using one as a planter.
For people with limited space, here is an interesting idea involving a pocket shoe organizer similar to the one pictured below:
I'd probably pick one made out of darker fabric, as I expect the lighter-colored varieties will begin to look very stained from the water running through them and bringing soil particles along with it. It would probably require frequent watering, too, depending on how breathable the fabric is.
Still, it is a great idea if you have limited space, and it's probably less expensive that anything at the garden centers that would serve a similar purpose.
I suppose one can always find another home for all of those shoes.
